Precision stages often have a linearly moveable stage supported on a fixed stage. Sometimes two linearly movable stages are supported on a fixed stage, with one movable stage moving in the x-direction and the other moving in the y-direction. Sometimes a single movable stage is mounted in fixed support for z-direction motion. The movable stages often have provisions for coarse and fine positioning using different control devices.
U.S. Pat. No. 4,700,585 to H. Marzhauser shows a drive system for slides and x-y stages in microscopes and similar instruments having the possibilities of both fine control and rapid displacement of the slides over larger distances. The drive system comprises a friction wheel and a friction track provided between the slide and the stationary slide guide. A friction wheel together with an actuation knob are solidly fixed on a common shaft and this common shaft is displaceable against a spring force so that the friction wheel is out of contact with the friction track. A brake shoe is provided for each shaft and a clamping element is provided for each brake shoe. The shafts are supported in ball bearings. The brake shoes are closed plastic rings and the clamping elements press uniformly by their U-legs and from diametrically opposite sides against the plastic rings in the braking position, the direction of the force passing through the center axis of the coaxial shafts. Accordingly, the braking forces are applied uniformly from two sides and balance each other, whereby no force component arises which would laterally shift the coaxial shafts.
Some stage drivers use rack and pinion devices to regulate motion, while others use gears or actuators. An object of the invention is a simple, reliable and highly controllable stage driver.